Forced circulation steam generator



,Dec. 18, 1951 w. s. PATTERSON FORCED CIRCULATION STEAM GENERATOR FiledSept. 4, 1947 n n n n n INVENTOR.

Word 8. Patterson BY Auri a/bur flr ai hgy Patented net. 18, 1951FoRcEni' omciiizzrrioN STEAM GENERATOR Ward S. Pattersom chappaqua, N.YJassignor to CoinbustioncEligineering Superheater, Inc.',' acorporation of Delaware Applieation seibtemlier 4, 1947, Serial'NoI77231195 This invention relates-"to apparatus for gener atingsteam andparticularlytoa steam genera-' tor in which thereis acontrolldforced=circu="-- lation of the fluid through the steam generating tubes.

D form'of the invention,

In steam generators constructed to operatein Figurei is a Sectiontakeii'on"line-44 of F this manner it is essential to distribute thewater ure 1 showing how the steam"*generatorsfheat to the steamgenerating tubesin'sufii'cient quan absorbing tubes" are arranged forparallelflowtity so that each of the tubes;which'are' arranged"therethrough of the liquid to be vaporized. for parallel water flowtherethrbughiwill"be"sufii=' Fig. "5 is a longitudinalsection throughtheciently cooled by the water to protect'it against steam" generatorfsdistribution header' takem'on overheating andconsequent"damageunder-"all line 5- 5 'of-Figs."2 and 3 and'showing'howthe ratesof steaming. herein-disclosed 'screening imeans' extend'l0ngif A preferred way of accomplishing'such'detudinally of theheaderto span-"a multiplicity sira'ble distribution of 'waterto' all" of thetube" Sta'm generating tube ends? circuits which are connected'ior'paraller'water Figures 1 and illustrate an "embodimentbfflowtherethrough to a manifoldordistribution' the invention-arranged forsteam generation. header, has been to provide 'orificesor-resistancesThe ste g illustrateficbmprises'a fur? at the entrance to each-"ofthetubes. Th'eseori-- nace chamber! within which-"'fue1-is"burnewby"fices are of smaller diameterthan' the "tube, the -meanss'u0h as anoil'burner"2' arrangedtdde diameter being chosen'to'present asubstantial liver oil for combustioninthiurnaceinfi Well?- resistance tothe flow of water? variations in'" kn wn m r. he i 3*h v g"its atin thelatter resistance thenhave-a reduced-in- Surface Within the: fl pfluenceupon the total resistance oforifie and Zontal cy ical steam andwater" druinrs to tube and consequently upon the-flow" of water- *whichWater may be supplied from any suitable" through the tube as governed by'theoriflce, source" throughxfeed-pipe '6 and steammaybe It is essentialthen that the-orifice'remain'unwithdrawn throughp p "11"" obstructed byforeign matter-suchas'scaieparti The heating surface 4withini'the'boilercom cles -01" sludge, during operation *because'the DE m ipli i y' f p al'l' y-a ra d tubes amount of water flow'through thetube and the- 4 connected to a commondistribution header 8 tubes safetydepend upon it; Heretofore' screens and passingthence upwardly along'awall of the or strainers have been provided'with'in' thg'diSJ furnace-land theme" iI1baCk=9 nd-f0 t 'D SSe tribution header at each oftheorifidesywhbs upwardly through theupperportionbfthe fur= screenopenings are smaller thanth'e' -orificso' nace to connect to thesteam'rand wate'rdrum as to stopthe flow of foreign-matter to the0r1'-5. "A downcomer 9"is conneoted'at itsuppe'rfend' fice which wouldotherwiseobstruct'it. to thebottomportion of drum-5 and'at itsiower-"iIt has been found from experiencethat'it is end o the inlet of 'p pimpossible to insure againstpredominant'segre+ p p is connected at its"dischargeflendtodis fi gation of such foreign matter into some of thetribution header 3 by -l Tli' pu p distribution headers and orteirtca'lim'ited ioca- 401"! is driven as y' i ot shqwny and cirs-t tionin oneof the headers',asforexaiiipleiadjatk (Hates the d m intoi'healdefcent-the ends r near th middlgbf fha'd 'fi. g thence through allofthe'tubesii'fl" and'b'ac'k "into pending upon new conditions in theheadeLI'THe drum An Ofitak? mm/es thaproductsfif amount of theforeignj'm-atte'rorfSolidihatiial combustion from the furnace?v incirculation within thel steaniigeriei'ator may- 46 In Order to insurepropefdistribufibh"Of be insignificant yet. sufficient," when segregatedWatgr amongau of the tubes 9 theheatin'gflsurfi at one location within aheader, to cause trouface w h areconnectedin'parallelbetween"" ble. Suchsegregation has resulted in a local orlthe-header a t 1t fi l p m fice'strainer becoming plugged and failure-.of-the m such," as f Fag, PP Yig. associated tube from lack of water and-.overh eat- 13) o i ii t i hfl w-R We? f 9? ingentranceend of each tube," The present inven- It isan object of this invention to provide an n is concgmed w antimgmved F timproved strainer within a distribution header maintaining theseorifices m proper operating condition'by protectin'g'themfromforeignmate Whlch the -F F rialin the water-which mightobstructth'ein."

Refemmg -P the drawingsrlflustratmamra" Figs.'2 and 3'show'twopreferred-"embodiments" e e em'bodlm'ents 0f thejinventloni of 'myinvention' as arrangedwithin" the distri 1 1 S a dl mtwrepresentation1oft; I bution'header 8 and 8 respectively? In Fig.'2thefo d u t tea enerator.e: ,7 distributionii'eaders'risrectangciarin'formma Fig-. -;2 ant-enlargedmrossizseetlomthroughiia iioizing water supply tubes or pumvzcorm'ectihe sr 2 distribution' headerof Fig. '1 showing one form" of theinvention? Figf3 is an enlazgedwiross section-througmadistributionheaderof Figf-"ll showing another from circulation pump Illas shown in Fig. 1. The steaming or boiler tubes 4 are connected to theheader as by welding-and are in alignment with a cylindrical opening l4through wall l5 of distribution header 8'.

A semi-cylindrically shaped strainer I6 is mounted within the header 8and comprises a semi-cylindrical plate I! welded to a fiat closure plate[8 extending across the diameter of the strainer 16'. Arranged centrallyand longitudinally of the closure plate 18 are orifices I3 mounted intoholes l9 provided in said plate longitudinally thereof at spacedintervals. The orifice structure comprises a tubular portion 20 havingan outside diameter suitable for mounting in hole l9 in plate l8 andhaving an end portion 2| within which is the orifice opening I3. Thecylindrical plate I! of strainer 16 is provided with a multiplicity ofapertures 22 each of which is smaller in diameter than the diameter oforifice hole l3. Preferably the sum of the areas of said perforations isat least 75% of the area of the unperforated strainer tube containingsaid orifices.

This strainer I6 is mounted on header wall l5 by means of stud bolts 23projecting'from said wall and bands 24 which bear against the strainerto urge it toward the header wall IS. The strainer I6 is so placed thatthe orifice holes align with the respective ends of the tubes 4.Preferably a soft gasket 25 may be placed between the plate l8 ofstrainer 16 and the wall l5 of header 8'. Should the gasket 25 beomitted the strainer It would move into contact with the header wall l5and the cylindrical portion 20 of the orifice would enter the hole [4provided within the header wall I5 in alignment with tubes 4. Thediameter of the strainer I6 is such that it may be removed through thehand hole 26 at the end of the header 8.

The strainer of Fig. 3 (wherein like reference numbers indicate likeparts as in Fig. 2) is in all essentials similar to the strainer in Fig.2 excepting that this Fig. 3 strainer l6 now comprises a completecylinder structure. A multiplicity of spaced-apart nozzles 21 are Weldedon to the strainer, one opposite each of the holes M in the header walll5 (shown inFig. 3 as being curved). The cylindrical portion 20 of theorifice structure is mounted into these nozzles and projects beyond theend of the nozzles to provide a seat for a possible soft gasket 25.Should the gasket be omitted the cylindrical portion 20 will telescopeinto the hole M in header wall l5 and the outer face of nozzle 21 willrest against the inner face of the header wall 5. The support of thestrainer in Fig 3 is identical with the support of the strainer shown inFig. 2.

The strainers l6 and I6 of both the Fig. 2 and Fig. 3 designs may bemade several feet long or any length that maybe conveniently handled(see Fig. 5) Only two or three clamps per strainer are required so thatonly a few hand holes 28 will be required in header walls opposite tothe strainer. With my improved strainer but eight or ten strainers areall that would be required for a large-sized steam generating unit whencompared to the present requirement of three hundred to four hundredindividual strainers adjacent each tube end. Furthermore, but twenty orthirty hand hole openings located opposite each strainer support willtake the place of three hundred to four hundred closure plug openings asnow used whereone closure is requiredopposite theendofeachtuba. V .7.

With my improved strainer each orifice may receive its water through theadjacent apertures in the-strainer or, should these adjacent aperturesbe plugged by foreign matter, said orifice could receive its water fromapertures opposite the remaining orifices included by said strainer. Inthis manner the danger of obstructing one orifice with its individualstrainer is overcome. 1

Furthermore, it is possible with my improved arrangement of strainer toprovide two pressure taps in each header, one connected to the spaceoutside of the strainers and the other to the space inside of thestrainers, so that a pressure drop across the strainer may be notedwhich will give an indication of the degree of plugging. This is animproved feature for a boiler unit operating with high makeup of treated(non-evaporated) feed water.

While the preferred embodiment of my invention has been shown anddescribed, it will be understood that changes in construction,combination and arrangement of parts may be made without departing fromthe spirit and scope of the invention as claimed.

What I claim is:

1. In a steam generator having a steam and water drum and a plurality ofsteam generating tubes exposed to the heat of the products of combustionfrom a furnace, a distribution header connected to the inlet ends of theaforesaid plurality of tubes for flow of water therethrough in parallelcircuits, the discharge ends of said tube circuits being connected tothe steam and water drum; resistance means within each circuit disposedat the said inlet end of each tube that is connected to saiddistribution header and in fluid-flow relationship therewith; screenmeans mounted within the header to prevent foreign matter fromobstructing the resistance means, said screen means comprising a tubularperforate element extending longitudinally of the header to span amultiplicity of the steam generating tube ends and forming an envelopesurrounding an open and unobstructed passage from any open portion ofsaid tubular perforate element to any and all of said resistance means;means connecting each tube inlet end and its resistance means with theinner or discharge side of said tubular perforate element so that onlythe drum to the header through the aforesaid tubular perforate elementand tubes back to the drum; and connections from the steam and waterdrum to said forcing means and from said forcing means to that portionof the distribution headers interior which surrounds the outer or inletside of said tubular perforate screening element.

2. In a steam generator having a steam and water drum and. a pluralityof steam generating tubes exposed to the heat of the products ofcombustion from an associated'furnace, a distribution header connectedto the inlet ends of the aforesaid plurality of tubes for flow of watertherethrough in parallel circuits, the discharge ends of said tubecircuits being connected to the steam and water drum; means forming anorifice within each circuit said means being disposed adjacent the saidinlet end of each tube and in fluid-flow relationship therewith aperforate p76 Wall element mounted within theheader to prevent foreignmatter from obstructing the said orifice means, said perforate wallelement having an inlet side and an outlet side and extendinglongitudinally of the header to span a multiplicity of the steamgenerating tube ends at said wall elements outlet side and being adaptedto form an unobstructed passage to any and all of the aforesaid orificemeans from any open portion of said perforate wall element so that onlywater which has passed through the perforate wall from its inlet side toits outlet side can be admitted into the aforesaid orifice for eachtube; a pump for forcing a flow of water through the circuits indirection of from the drum to the header through the perforate wall andtubes back to the drum; and connections from the steam and water drum tothe pump inlet and from the pump discharge to that portion of thedistribution header which is on the inlet side of said perforate wallelement.

3. In a steam generator having a steam and water drum and a plurality ofsteam generating tubes exposed to the heat of the products of combustionfrom a furnace, a distribution header connected to the inlet ends of theaforesaid plurality of tubes for flow of water therethrough in parallelcircuits, the discharge ends of said tube circuits being connected tothe steam and water drum; resistance means within each circuit disposedat the said inlet end of each tube that is connected to saiddistribution header; an access hole in an end of said header; screenmeans mounted within the header to prevent foreign matter fromobstructing the resistance means and constructed to be removable throughsaid hole, said screen means comprising a tubular periorate elementextending longitudinally of the header to span a multiplicity of thesteam generating tube ends; means connecting each tube inlet end withthe inner or discharge side of said tubular screen so that only waterwhich has been passed through the screen perforations can be admittedinto the said resistance means for each tube; means for forcing a flowof water through the circuits in direction of from the drum to theheader through the said tubular screen and tubes back to the drum; andconnections from the steam and water drum to said forcing means and fromsaid forcing means to that portion of the distribution header interiorwhich surrounds the outer or inlet side of said tubular screen element.

4. In a steam generator having a steam and water drum and a plurality ofsteam generating tubes exposed to the heat of the products of combustionfrom a furnace, a distribution header connected to the inlet ends of theaforesaid plurality of tubes for flow of water therethrough in parallelcircuits, the discharge ends of said tube circuits being connected tothe steam and water drum; resistance means within each circuit disposedat the said inlet end of each tube that is connected to saiddistribution header; means forming a fluid-flow connection between eachtube inlet end and the said resistance means thereat; an access hole inan end of said header; screen means mounted within the header to preventforeign matter from obstructing the resistance means and constructed tobe removable through said hole, said screen means comprising 7 aperforated tubular member extending longitudinally of the header to spana multiplicity of the steam generating tube ends and having an inner ordischarge side connected with all of said tube end resistance means toestablish unobstructed communication therewith; means for forcing a flowof water through the said plurality of circuits in direction of from thedrum to the header through said perforate tubular member and tubes backto the drum so that only water which has passed through the tubularmember's perforations can be admitted into the said resistance means foreach tube; and connections from the steam and water drum to said forcingmeans and from said forcing means to that portion of the distributionheader interior which surrounds the outer or inlet side of saidperforate tubular member.

5. In a forced circulation boiler, the combination of a steam and waterdrum; a distributing header; a plurality of heat absorbing tubes for thegeneration of steam from water having outlet ends communicating withsaid steam and water drum and having inlet ends connected to a row ofopenings in said distributing header; flow restricting means associatedwith each of the said inlet ends of said tubes; forced circulation meanshaving a suction side connected to said steam and Water drum and adischarge side connected to said distributing header; and a perforateddivision wall within said header disposed in a position opposite thesaid row of tube inlet openings and interposed between the dischargeside con-' nection of said forced circulation means and the said row oftube inlet openings whereby water recirculated from said steam and waterdrum by way of said circulation means can enter any one of said heatabsorbing tubes by passing through any one of the perforations of saidheaders division wall.

6. Ina steam generating boiler, the combination of a steam and waterdrum; a distributing header; heat absorbing tubes for the generation ofsteam from water having discharge ends connected to said steam and waterdrum and having inlet ends connected to a row of openings in saiddistributing header; flow restricting means at the inlet end of each ofsaid tubes; forced circulation means having a suction side connected tosaid steam and water drum and a discharge side connected to saiddistributing header; and a perforated strainer member within said headerextending along the row of tube inlet openings from end to end thereofand interposed between the discharge side connection of said forcedcirculation means and the said row of heat absorbing tube inlet openingswhereby Water recirculated from said steam and water drum by way of saidcirculation means can enter any one of said heat absorbing tube inletopenings by passing through any one of the perforations of said header'sstrainer member.

. WARD S. PATTERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 188,144 Jennings Mar. 6, 1877248,573 Burkhardt Oct. 25, 1881 1,988,659 La Mont Jan. 22, 1935

